#include<stdio.h>
int main()
{
	int i = 1,sum = 0;
	int n,m;
	scanf("%d %d",&n,&m);
	i = m;
	while(m>4&&n<=98)
	{
		if(i%2==0)
		{
		 	sum+=i; 
			i++;
		}
		printf("%d",sum);
		return 0;
}
	
	
	
	
	
	
	
	
} 
